Polymers containing polycyanotetrahydrofuran rings and the preparation thereof



United States Patent 3,419,536 POLYMERS CONTAINING POLYCYANOTETRA-HYDROFURAN RINGS AND THE PREPARA- TION THEREOF William Joseph Linn,Wilmington, Del., assignor to E. I. du Pont de Nemours and Company,Wilmington, Del., a corporation of Delaware No Drawing. Originalapplication Sept. 28, 1962, Ser. No. 227,070, now Patent No. 3,317,567,dated May 2, 1967. Divided and this application Mar. 30, 1967, Ser. No.

13 Claims. 01. 260-85.1)

ABSTRACT OF THE DISCLOSURE Modification of unsaturated polymers byreaction of a polycyanoethylene oxide with 1-50% of the unsaturation attemperatures of 80250 C. Molded objects and films can be produced fromthe modified polymers.

CROSS-REFERENCE TO RELATED APPLICATION This appplication is a divisionof my copending coassigned application Ser. No. 227,070, filed Sept. 28,1962, now US. Patent 3,317,567.

FIELD OF THE INVENTION This invention relates to novel polymerscontaining polycyanotetrahydrofuran rings and to the process for theirpreparation. I

SUMMARY OF THE INVENTION This invention is directed to modified polymerseach consisting of:

a substrate precursor polymer contining, before modification, aplurality of initial sites of carbon-carbon double bond saturationeither ethylenic or aromatic, and

containing pendant, after modification, from 150% of the initial sitesof the carbon-carbon double bond unsaturation, attached to each of thecarbons therein by one bond and forming therewith apolycyanotetrahydrofuran ring, a divalent radical of the formula whereinA is hydrogen, CN, perfiuoroalkyl of up to 13 carbons, p-XH C i.e.,

or R where R is alkyl of up to 18 carbons and X is hydrogen, halogen,nitro, R-- or RO- where R- is as defined above; and B is cyano,perfiuoroalkyl of up to 13 carbons or i Roo where R- is as definedabove.

These modified polymers, which generally melt or soften at highertemperatures and are more resistant to organic solvents than theprecursor polymers, can be fabricated into molded objects and films.

3,419,536 Patented Dec. 31, 1968 DESCRIPTION OF THE PREFERREDEMBODIMENTS Modification of polymers, especially commercially availablepolymers and resins, is a means of producing new polymers havingimproved properties compared to the precursor polymers. For example, themodified polymer can have higher or lower melting points or meltingranges, requiring different fabrication conditions. Improved solubilitycharacteristics sometimes are observed. Modification of a polymer is amethod of introducing reactive sites into polymer chain.

The polymers of this invention may be regarded as adducts of: (a) apolycyanoethylene oxide of the formula wherein A and B are as definedabove and (b) a polymeric compound having aromatic or ethylenicunsatura- When a precursor substrate has both ethylenic and aromaticunsaturation, such as a butadiene-styrene copolymer, both types ofunsaturation are sites for the formation of the tetrahydrofuran rings.

The products of this inveniton are prepared by reacting apolycyanoethylene oxide of the formula with l50% of the unsaturation ofa precursor polymer. Polymers which can be used include:poly(1,3-butadiene), poly(2-chloro-1,3-butadiene), poly(2-bromo-1,3butadiene), polystyrene, polyisoprene, poly(2,4 hexadiene),poly(2,3-difluoro-l ,3-butadiene) ethylene/ 1 ,S-hexadiene copolymers,styrene/1,3-butadiene copolymer or acrylonitrile/1,3-butadienecopolymer. The process is conducted at elevated temperatures but isconveniently conducted at temperatures of about 80 C. to about 250 C.and preferably at temperatures of about 100 C. to about 200 C.

Polymers which can be modified by reaction with a polycyanoethyleneoxide preferably are the various commercially available resins includingpolystyrene, poly(2- chloro 1,3 butadiene), poly( 1,3 butadiene),poly(isoprene), styrene/1,3-butadiene copolymers and acrylonitrile/1,3-butadiene copolymers. Each of the resins is available in variousmodifications having slightly different molecular weights, moldingcharacteristics, melting ranges and viscosities. The process of thisinvention is equally applicable to the various forms of thesecommercially available resins, i.e., the commercially available polymersof differing molecular weight or those possessing different fabricationcharacteristics.

Polycyanoethylene oxides of the foregoing description can be obtained byprocedures described in U.S. 3,238,228. Among these polycyanoethyleneoxides, tetracyanoethylene oxide is especially preferred for thepreparation of the polycyanotetrahydrofuran-modified polymers becausethe olefin from which this oxide is prepared, i.e., tetracyanoethylene,is available commercially and is therefore more accessible the otherpolycyanoole-fins. Because of their greater accessibility,perfluoroalkyl groups containing up to 13 carbons each are preferred inthe polycyanoepoxide starting materials having such substituents.Included in the definition of perfluoroalkyl are trifiuoromethyl,perfluoroethyl, perfluoropropyl, perfluorobutyl, perfiuorodecyl,perfiuorododecyl, perfluorotridecyl and the like.

The reaction pressure is not critical and can be in the range from belowto above atmospheric pressure. Accordingly, the reaction is accomplishedin a reaction vessel suited to the chosen mode of operation. Although itis advantageous to carry out the reaction in a closed vessel underpressure which is the autogenous pressure of the reactants, a reactorwhich is not closed pressurewise against the atmosphere can also beused. However, it is important to prevent the escape of any reactantfrom the sphere of reaction, whether in a closed or open reactionvessel. When the vessel is otherwise open to the atmosphere, thereactants are confined by use of any suitable means, such as a solventand/ or a reflux condenser.

The reaction time is not critical and will ordinarily vary from aboutone hour to several days depending on the specific temperature andpressure that are employed, longer times being needed to obtainsubstantially complete reaction at lower temperatures and pressures.

A reaction medium is unnecessary but can be used to advantage; and themedium can be an excess of a nonreactive solvent such as1,2-dibromoethane, or a potentially reactive solvent that is lessreactive with polycyanoethylene epoxides than the chosen unsaturatedpolymer, e.g., toluene can be used as a solvent in the reaction oftetracyanoethylene oxide with an ethylenically unsaturated polymer. Thereaction can be conducted on a heated rubber mill.

The proportions of polycyanoethylene oxide and unsaturated polymer arenot critical, and a stoichiometric excess of either can be used. It isnot unusual to use an excess of the unsaturated polymer. In general, theamount of the polycyanoethylene oxide reacting with the precursorpolymer is less than the amount used.

When the unsaturated polymer has more than one carhon-carbon doublebond, the bonds being cumulated or conjugated, only one of the doublebonds will normally react with the epoxide even when the epoxide ispresent in stoichiometric excess. However, when the unsaturated reactanthas a plurality of aliphatic double bonds that are noncumulated ornonconjugated, each of such double bonds can react simultaneously withseparate molecules of the epoxide, e.g., unsaturated polymers such aspolybutadiene can react at any or all of the separate unsaturatedcenters. Hence all noncumulated and nonconjugated aliphatic bonds andone each of a series of cumulated or conjugated aliphatic double bondsin a polyunsaturated reactant are reactive.

The new polymers of this invention will vary in physical propertiesaccording to the nature of the original polyunsaturated polymer and theextent to which the reactive double bonds are converted topolycyanotetrahydrofuran units. Generally, such products are highermelting and less soluble than the parent polymers.

As was noted above, the epoxide reactants used in the process of thisinvention are prepared by the method disclosed and claimed in US.3,238,228. This method consists of reacting a compound of the formulawherein A and B are as defined above, with aqueous hydrogen peroxide (atleast 3% H 0 by weight, conveniently 30% by weight) in solution in asingle phase, preferably at a temperature of 20 to +50 C. and a pH of6-8. The solvent used to prepare the single phase solution of reactantsis a water-miscible, inert organic liquid such as acetonitrile. Atypical preparation is as follows:

A solution of 256 parts of tetracyanoethylene in 1180 parts ofacetonitrile is cooled at 0 C. and 344 parts of 30% hydrogen peroxide isadded all at once. A transient violet color appears which soon fades toyellow. The solution is stirred for five minutes and diluted with 10,000parts of ice water. The oil which separates soon solidifies and iscollected by filtration and dried to give 200 parts (70% yield) ofcolorless crystals of tetracyanoethylene oxide. After recrystallizationfrom ethylene dichloride, the product melts at 177-178 C.

The invention is illustrated in greater detail in the followingexamples, in which percentages and quantities of reactants (parts) aregiven in terms of weight unless otherwise indirected.

EXAMPLE 1 Tetracyanoethylene oxide modified polystyrene To a solution of10 parts of polystyrene in 540 parts of 1,2-dibromoethane was added 13.8parts of tetra-cyanoethylene oxide dissolved in about parts of1,2-dibromoethane. The mixture was stirred and heated to remove thesolvent by distillation at atmospheric pressure (B.P. of1,2-dibromoethane l3l.5 C.). The residual product was extracted withethanol in a Soxhlet apparatus. Analysis of the dried ethanol-insolubleproduct showed a nitrogen content corresponding to a reaction of 10parts of polystyrene with 2.1 parts of tetracyanoethylene oxide or to areaction of about 15% of the unsaturation.

Analysis.Calcd for 10/2.1 polystyrene/tetracyanoethylene oxide: Calcd:C, 85.0; H, 6.36; N, 6.77. Found: C, 80.8; H, 6.49; N, 6.77.

EXAMPLE 2 Tetracyanoethylene oxide modified polyisoprene (A) A blend of15 parts of xylene-soluble raw crepe rubber (polyisoprene) and 15.2parts of tetracyanoethylene oxide was prepared on a rubber mill havingheated rolls 6" long by 2.5 in diameter. The mixture was milled minutesat 58 C., 4 minutes at 100 C. and 5 minutes at 105-1l0 C., and was thensheeted out. The sheeted product, after extraction with methanol for twoweeks in a Soxhlet apparatus, was found to be insoluble in xylene.

(lure of Example 3B to yield modified polymers containingtet-rahydrofuran units and having higher-melting points and lowersolubility than their respective parent polymers.

(B Blended mixtures of raw crepe rubber and tetra- 5 EXAMPLE 4cyanoethylene Oxide Were P p red on a rubber H11 1, Tetracyanoethyleneoxide modified ethylene/1,5- molded sheets of the blends were made 1n al'IlOlCllIlg press h di copolymer under various conditions, tensilestrength and elongation of the molded samples were determined, andelemental 10 An elastomerlc copolymel was P pa from 8 Ig analyses wereobtained. The data are presented in Table I, f ethylene and 1 of li atwherein; with a vanadyl tr1chlor1de-t1tan1urntetraphenoxlde-dlethylaluminum chloride catalyst. The polymer containedT9NEO=weight percenttetraganoethylene qxlde blended about 25% hexadieneunits (estimated by infrared spec- T C.=mold1ng temperature 1n degreescentlgrade h d h 1 47 Min =molding time in minutes troscoprc analys1s),and a an 1n erent v1scos1ty at Tensile=tensile strength in lbs. per sq.in. of cross-section at concentranon m 'Chloronaphthalene Elong'=percentelongation at break A solutlon of 3.3 parts of the copolymer (contamlngthe C, H, Nzpercem carbon, hydrogen and nitrogen, 1.651360 eqruvalent of0. 02 mole of v1nyl groups) and 2.9 parts i 1 (0.02 mole) oftetracyanoethylene oxide in 110 parts of Percent of unsaturationreacted=percent of initial unsat- 20 chlorobfinlene Was heated atTefiIlX for two h uration in precursor polymer whi h r a t d ithreaction mixture was then cooled and poured into excess TCNEO. ethanolto precipitate the polymeric material, which was TABLE I Percent of C HN Unsaturation No. TCNEO T 0 Min Tensile Elong Reacted Calcd. FoundCalc'd. Found Caled. Found Calcd. Found 0 120 60 2,157 1, 219 0 140 1,908 1, 159 0 150 15 1,474 1, 010 87.2 83.8 11.5 11. 3 1.13 1. 29 1. 4 1.6 2.9 100 30 142 522 2.9 120 30 102 559 2.9 120 2.9 140 30 so 427 11.1120 60 236 94 I, 84 0 82 4 10.5 10 4 4 32 3 92 5 7 5 3 11.1 140 30 26499 11.1 150 30 20 120 60 811 57 20 140 30 765 50 6 77 1 9.45 9 02 7 78 711 11.8 10.8 20 150 30 EXAMPLE 3 separated, washed successively withethanol, acetone and Tetracyanoethylene oxide modified polychloroprene(A) A blend of 25 parts of xylene-soluble polychloroprene and 40.6 partsof tetracyanoethylene oxide was prepared on a rubber mill having heatedrolls 6" long by 2.5" in diameter. The mixture was milled 32 minutes at50 C. and 15 minutes at 110 C., and was sheeted out at 60 C. The sheetedproduct, after extraction with methanol for two weeks in a Soxhletapparatus, was found to be insoluble in xylene.

(B) Blended mixtures of polychloroprene and tetracyanoethylene oxidewere prepared at 50 C. on a rubber mill and tested, as in Example 2-B.The data thus obtained are presented in Table II (the table headingshave ethanol, and dried under reduced pressure. The resultant 3.5 partsof material was elastomeric. Infrared spectroscopic analysis of theproduct showed a lack of absorption due to vinyl groups (found in theoriginal. copolymer at 910, 990 and 1642 cm. a moderate strong sharpabsorption at 2250 cm.- indicative of cyano groups, and broad bandscentered at 1010, 1070 and 1220 cm. which are believed to be indicativeof the tetrahydrofuran structure. The product was found to be insolublein tat-chloronaphthalene at C., and pressed films were foundqualitatively tougher than films of the original copolymer. Elementaryanalysis showed 4.8% nitrogen, corresponding to about 27 percent of theinitial double bonds com- 55 bined with tetracyanoethylene oxide in. thetreated the same meaning as 1n Table I). copolymer.

TABLE II C H N UPergenttoi No. TCNEO T 0 Min Tensile Elong. l ia cgdCalcd Found Calcd. Found Caled. Found Caled. Found 3:8 54 1 53.5 5.495.5 1.13 0.70 1.83 1.13 3:8 53.9 53.4 5. 03 5. 37 4.3.9 3. 22 7.7 5.711.1 30 11.1 15 295 11.1 150 30 382 221 53.4 52.6 4.52 4.80 7.78 5.9815.3 11.8 20 120 60 1, 586 105 20 150 30 1,929 98 Halohydrocarbonpolymers in addition to polychloro- 70 EXAMPLE 5 prene can be reactedaccording to the process of this in- Ventiom For examplg, polybromprenel fi Tetracyanoethylene oxlde modlfied 1,3-butadrene/styrenebromo-1,3-butadiene) and poly-2,3-difiuorobutadiene copolymer (P y i l-b fi i can be reacted (A) A solution of one part of butadiene/styrenecowith a tetracyanoethylene oxrde by following the proce- 75 polymerhaving a butadiene content of 26% and 0.55 part of tetracyanoethyleneoxide in 55 parts of chlorobenzene was heated at reflux for three hours.The cloudy reaction. mixture was cooled and poured into an excess ofethanol. A polymeric solid was precipitated which was washedsuccessively with acetone and ethanol. The solid was found to be swollenbut insoluble in acetone, and additional tests showed it to be insolublein a variety of polar and nonpolar solvents.

(B) A butadiene/acrylonitrile copolymer having an 82% butadiene contentwas treated with tetracyanoethylene oxide by the procedure described inExample A, above. The resultant product was likewise insolubilized.

EXAMPLE 6 Tetracyanoethylene oxide modified poly (2,4-hexadiene) A gummyelastomeric polymer was prepared from 3.5 parts oftrans-trans-2,4-hexadiene in 55 parts of chlorobenzene at 3() C. with avanadyl trichloride-diethylaluminum chloride catalyst. A solution of 1.9parts of the polymer in 55 parts of chlo-robenzene was heatd to 100 C.,and 1.44 parts of tetracyanoethylene oxide was added. The reactionmixture was heated at reflux for 8 hours, and was then coled an dilutedwith excess ethanol. The resultant precipitate was washed with ethanoland dried under reduced pressure. The product was dark in color andpartially insoluble in tetrahydrofuran, but the soluble portion could becast to a dark, clear, brittle film. Infrared spectroscopic analysisshowed that the treated polymer contained about 50 less transunsaturation than the untreated polymer; and the presence in the treatedpolymer of bands at 1-010, 1070 and 2250 cm.- showed the presence of thetetracyanotetrahydrofuran grouping.

The process of this invention is applicable to copolymers having froml99% by weight of cornonomer. These copolymers are prepare-d bywell-known addition polymerization methods.

The procedures of Examples l-6 can be conducted using instead oftetracyanoethylene oxide an equivalent amount of one of thepolycyanoethylene oxides listed below:

N CN

NC CN O C1F15 Polycyanotetrahydrofuran substituted polymers obtained byreaction of polycyanoethylene oxides with poly-unsaturated polymersgenerally have higher melting oints and melting ranges and lowersolubility than the precursor polymers and can be used as highermelting, solvent resistant embodiments thereof. The modified polymerscan be obtained in the form of waxes, or plastics which are useful forthe production of molded objects such as rods or sheets or for theproduction of self-supporting films. Since the physical properties ofthe polymers vary with the amount of combined polycyanoethylene oxide(cf. Examples 2 and 3), such modified polymers are useful for a varietyof specific uses according to the properties desired.

EXAMPLE A The modified polymer prepared in Example 4 was meltpressed atC. A tough, clear, self-supporting film was obtained.

The foregoing detailed description has been given for clarity ofunderstanding only and no unnecessary limitations are to be understoodtherefrom. The invention is not limited to the exact details shown anddescribed for obvious modifications will be apparent to those skilled inthe art.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A modified polymer consisting of:

a substrate precursor polymer containing, before modification, aplurality of initial sites of carbon-carbon double bond unsaturationeither ethylenic or aromatic, and

containing pendant, after modification, from 150% of the initial sitesof the carbon-carbon double bond unsaturation, attached to each of thecarbons therein by one bond and forming therewith a polycyano- 9tetrahydrofuran ring, a divalent radical of the formula A B \l I/ NC/ CNwherein A is hydrogen, CN, perlluoroalkyl of up to 13 carbons, p=XH Ci.e.,

or R- where R- is alkyl of up to 18 carbons and X is hydrogen, halogen,nitro, R-- or R-O where -R is as defined above; and

B is cyano, perfiuoroalkyl of up to 13 carbons or where R is as definedabove.

2. A modified polymer of claim 1 wherein the substrate polymer ispoly(1,3-butadiene), poly(2-chloro-l,3- butadiene),poly(2-bromo-1,3-butadiene), polystyrene, polyisoprene,poly(2,4-hexadiene), poly(2,3-difluoro-l,3- butadiene), anethylene/1,5-hexadiene copolymer, a styrene/1,3-butadiene copolymer oran acrylonitrile/1,3- butadiene copolymer.

3. A modified polystyrene polymer of claim 1.

4. A modified po1y(2-ch1oro-1,3-butadiene) polymer of claim 1.

5. A modified styrene/1,3-butadiene copolymer of claim 1.

6. A modified polyisoprene polymer of claim 1.

7. A self-supporting film formed from a modified polymer of claim 1.

8. The tetracy-anoethylene oxide modified polymer of claim 3 whereinpendant from about 120% of the initial sites of carb0n-carb0n doublebond unsaturation are tetraeyanotetrahydrofuran rings.

9. A tetracyanoethylene oxide modified polymer of claim 4 whereinpendant from about 1 to of the initial sites of carbon-carbon doublebond unsaturation are tetracyanotetrahydrofuran rings.

10. A tetracyanoethylene oxide modified polymer of claim 5 whereinpendant from about 1 to 30% of the initial Sites of carbon-carbon doublebond unsaturation are tetracyanotetrahydrofuran rings.

11. A tetracyanoethylene oxide modified polymer of claim 6 whereinpendant from about 1 to 50% of the initial sites of carbon-carbon doublebond unsaturation are tetracyanotetrahydrofuran rings.

12. A self supporting film formed from a modified polymer of claim 8.

13. The process for preparing a polymer of claim 1 comprising heating ata temperature of -250 C. a mixture of (a) a polycyanoethylene oxide ofthe iiormula wherein A and B are as defined in claim 1; and

(b) a polymer selected from poly( 1,3-butadiene poly(2-chloro-1,3-butadiene) poly(2-brorno-1,3-butadiene), polystyrene,polyisoprene, poly(2,4-hexadiene), poly(2,3-difluor0-1,3-butadiene), anethylene/ 1,5 -hexadiene copolymer, a styrene/1,3-butadiene copolymer oran acrylonitrile/1,3-butadiene copolymer.

No references cited.

JOSEPH L. SCHOFER, Primary Examiner. L. ED'ELMAN, Assistant Examiner.

U.S. Cl. X.R. 26083.3, 88.2, 92.3, 93.5, 94.7.

may UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.ii2,536 Dated December 31, 1968 Inventofls) William Joseph Linn It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 9,1ine 9, Claim 1, "p=XH should read SIGNED AND SEALED OCT 2 11969 (SEA!) Luca:

Edwu'dMFletchfl I W LLIAM E. saaumm, m. Attesting Officer comissionwPatents

